Jacket crown



M. B. BRENNER 2,283,786

JACKET GROWN INVENT OR.

' Filed Jan. 28, 1942 Patented May 19, 1942 UNETED STATES PATENTGFFICE JACKET CROWN Milton B. Brenner, Chicago, 111.

Application January 28, 1942, Serial No. 428,476

Claims. (01. 32-42) My present invention relates to the provision of an armored jacket crown. As will hereafter be seen, this invention relates wholly to a special and rigorously delimited field for, while jackets may be occasionally employed on the posterior teeth of both upper and lower jaws, a great proportion of jackets are limited to the twelve anterior teeth, specifically so called, which present characteristic special conditions indicating or requiring the use of armored jacket crowns.

A jacket crown is an accurate descriptive name and indicates a hollow tooth form mounted upon a reduced and specially prepared remainder of the original, natural tooth. It will be realized that, as the upper anterior teeth (the anterior teeth being the central six teeth in both upper and lower jaws) with human beings are almost uniformly overshot, the upper anterior teeth, with a great majority of people, are, by far, the most prominent teeth of the entire set. However, at times, abnormal development of the dental arches or malocclusion of the teeth will give rise to protrusion of the lower teeth,'such condition causing the lower anteriors to be the most prominent teeth of the entire set. Therefore, any feature which renders any of the anterior teeth better in appearance, or more sturdy and usable, is both useful and desirable.

The upper anterior teeth being generally overshot, the points or areas of occlusion or contact with the lower teeth occur, in a vast majority of cases, behind and well up at the gingival, just below the cervical ridge. At this point of contact or occlusion, the nerve and pulp chamber,

in which is located the biologically living portion of the teeth, is particularly near the surface, and, generally, the shaping of the remainder of the original, natural tooth cannot be carried to a point of removing much of the outer surface, or the pulp chamber and nerve will be rendered very liable to injury. As a result, the jackets are required to be particularly thin and delicate at the areas of occlusion or contact, which areas are, as a matter of fact, those which are compelled to undergo the greatest portion of service and sustain the greatest strains when chewing, as distinguished from biting, because the anterior teeth occlude when the food is being ground between the posterior teeth which have much more extensive horizontal occlusal surfaces.

Porcelain jackets which are satisfactorily hard to withstand abrasion are, unfortunately, of a brittle and fragile nature which is particularly noticeable at spots where the mass is necessarily reduced and thin. In other words, at the areas of contact or occlusion between the teeth.

Dentists have, therefore, sought other substances than porcelain for the making of jacket crowns, and among such substances, more or less recently, appeared several moldable compositions known as plastics, which usually congeal or harden upon the reduction of temperature from a relatively great heat. Certain of such substances are much tougher than an equal thickness of porcelain, but none of such substances have yet been produced which have the requisite hardness to satisfactorily withstand the abrasion occurring at the contacting or occluding areas.

The object of my present invention is to provide a molded or cast jacket for a tooth which may be formed from a suitable plastic with a metallic, such as gold or alloy, surface at the occluding areas. As will hereafter be seen, I have provided such molded or cast plastic composition jacket crown with a metallic or alloy surface at the occluding areas, which not only provides a satisfactorily hard grinding surface, but also enhances the general stability of the tooth. Being on the lingual or rear surface of the jacket, such metallic or alloy surface is not visible and, also, in no way interferes with any of the delicate carving which is desirable and necessary in securing the best structure, as well as appearance, with relation not only to-the laterally adjacent teeth with which the jacket is associated, but also structurally and dynamically in relation to the opposing teeth with which the jacket is required to contact or occlude.

It must never be lost sight of that the human jaws are a mechanically complicated structure for both biting and grinding in suitably comminuting food. It will be seen, at once, that my objects and the results which I obtain are wholly different from the objects and results involved in providing gold crowns with a porcelain veneer front, which latter arrangement practically relegates the function of the porcelain to a mere matter of appearance, and has been found unsatisfactory for anterior teeth.

I attain the production of a molded plastic crown with a metallic or alloy surface at the occluding areas by means of a structure substantially equivalent to that shown in the accompanying drawing in which- Fig. 1 is a perspective of the metallic portion before molding or casting.

Fig. 2 is a perspective showing the rear face of a molded plastic jacket embodying my invention.

Fig. 3 is a, section on line 33 of Fig. 2.

Fig. 4 is a front elevation to an enlarged scale showing a jacket and tooth assembly.

Fig. 5 is a vertical central section of a jacket and tooth assembly as shown in Fig. 4.

Fig. 6 is a horizontal section of a jacket and tooth assembly on line 6-6 of Fig. 5 and.

Fig. 7 is a vertical central section showing the relation of two occluding or contacting teeth.

Similar reference characters refer to similar parts throughout the respective views.

As will be seen, Fig. 1 is drawn to an exaggerated scale for greater clearness and shows a blank of sheet gold or an alloy of non-corrosive metals comprising the protective armor or surface plate l0 from each end of which extends central tangs II, which extend at right angles to a plate I0 and corner tangs l2 which are also turned at right angles to the plate I0 but in an opposite direction to the tangs II.

The procedure of making a molded jacket crown comprises the building up upon the prepared remainder of the tooth l3, a jacket of desired size and form, with a suitable substance called carving wax. After such jacket of wax has been carved, the occluding or contacting surface thereof with the opposite tooth is carefully ascertained, the protective plate I0 is heated slightly over a Bunsen flame, and the tangs [2 are pressed into the jacket formed of the wax so that the plate ID will be at the occluding or contacting area. The jacket formed of carving wax, with the plate I!) associated therewith as above described, is then invested in a flask with plaster of Paris, or other suitable matrix forming material, in which the tangs l l are imbedded. The wax from the matrix is then expelled by heat, but by reason of the tangs II the plate l0 and tangs l2 are maintained in proper relation with the matrix and the jacket molded therefrom.

The proper opening of the flask and providing a core therefor in the molding of a jacket is in accordance with a Well known procedure and requires no specific description.

After the molding of the jacket, the portion of the matrix in which the tangs H are imbedded is destroyed, as is usual, the tangs H are cut off and the cut edges are burnished and polished r into a desired smooth surface with the adjacent substance of the jacket crown.

It will be recollected that it was heretofore stated that the use of jacket crowns was much more frequent with the upper anterior teeth, but it should also be observed that when the lower anterior teeth are in normal occlusion, or the posterior teeth with horizontal occluding surfaces are involved, entirely different mechanical conditions are present, and no visible armor of any kind can be used.

Abnormal development of the dental arches or malocclusion of the teeth will sometimes give rise to protrusion of the lower teeth where it then becomes necessary and possible to use a protective plate on the lingual surface of the lower teeth, this surface being in occlusion with the labial incisal edge of the upper teeth.

It will be seen that I have invented an armored jacket which may easily be prepared or molded with, or by means of, commercial plastics and, nevertheless, has not only the increased toughness resulting from the use of such material but hardness and resistance at the occluding area so as to permit normal use of the teeth without the hitherto rapid wearing away resulting from the abrasion incident to normal use.

Having described my invention, what I claim as new and desire to secure by Letters Patent 1. A jacket crown for a tooth contacting or occluding on the lingual face capable of being molded with a commercial plastic comprising a tooth form having a recess at the top thereof adapted to receive the prepared portion of an original tooth, a metal plate disposed at the area of occlusion of said tooth form, with tangs extending therefrom into the substance of said tooth form.

2. A jacket crown capable of being molded with a commercial plastic comprising a tooth form, a metal plate disposed at the area of occlusion of said tooth form and tangs extending therefrom into the substance of said tooth form.

3. A jacket crown for a tooth contacting or occluding on the lingual face thereof comprising a tooth form, a metal plate disposed at the area of occlusion of said tooth form and developments extending from said metal plate into the substance of said tooth form.

4. A surface armor for the occluding surface of a jacket crown for a tooth contacting or occluding on the lingual face thereof comprising a central surface portion, corner tangs adapted to be surrounded by the substance of a molded jacket crown and central tangs extending in the opposite direction from said corner tangs and adapted to be invested in the matrix for molding said jacket crown.

5. A surface armor for the occluding surface of a jacket crown for a tooth contacting or occluding on the lingual side thereof comprising a central portion and members extending from said central portion in opposite directions therefrom for imbedding respectively inan invested flask and the tooth form molded therein.

MILTON B. BRENNER. 

